Method of forming ball point pens



March 28, 1961 A. G. scHucK Filed July 31. 1953 March 28, 1961 A. G.SCHUCK 2,976,610

METHOD OF FORMING BALL POINT PENS Filed July 51. 1953 2 Sheets-Sheet 2IN VEN TOR. Jun 01w 6. 621/006 24 BY 15 L- y W m j 0411 I235 METHOD OFFORMING BALL POINT PENS Anthony G. Schuck, Alhambra, Calif., assignor,by mesne assignments, to John M. Lee, Los Angeles, Calif.

Filed July 31, 1953, Ser. No. 371,650

3 Claims. (Cl. 29-441) My invention relates generally to ball pointwriting instruments, and more particularly to a method for formingprecision ball points.

The'major problem of the ball pen industry is improvement and control ofthe writing qualities of ball point assemblies. Through extensiveresearch and the enormous production of recent years, optimumcharacteristics for the internal and external design of the points havebecome well known. However, it has been impossible to maintain closeproduction control over the writing quality of the points whileachieving the high rate of output that is economically necessary.

In choosing to illustrate the principles of my invention, 1 will referto a type of point construction which has become conventional for use inmodern ball point pens. it should be understood that I do not intend tothereby limit the invention to a particular point construction, as thelatter may be modified and improved from time to time while stilladvantageously using the method and apparatus set forth herein.

Considering a greatly enlarged section of a point assembly as shown inthe drawings, the nose of the point is formed with an internal socket inwhich is seated a spherical ball. When writing, pressure is applied, theball rotates or rolls to pick up ink from an internal reservoir andcarries it forwardly or outwardly for transfer to the writing paper. Torestrain inward movement of the ball, a bottom section of the socketforms a frictionless seat against which the ball is free turning. Thisseat portion of the socket is usually separated from the side wallportions of the socket.

To hold the ball in place within the point, the wall of the nose isextended forwardly beyond a transverse plane passed through the centerof the ball and folded inwardly to form a retaining ring portion. Thecentral plane through the ball may be referred to as the equator of theball, and the portion of the nose wall extending forwardly beyond theequator as the point rim. Normally, the rim has a frusto conical surfacetapered inwardly toward the axis of the point, and terminated by a thininturned edge whichlies immediately adjacent the ball. In order todistinguish between the two portions of the rim, I will herein refer tothe angled frusto conical surface of the rim as the rim angle, and theterminal surface of the rim as the rim edge or lip.

The internal side wall surface of the rim forms with the adjacentcentral portion of the ball, a metering or orifice section to controlthe rate of ink flow as determined by the clearance between the twomembers. As can be appreciated, the control of this clearance iscritical in obtainin a pen point having uniformly good writingqualities. In addition to the control of clearances, it is essentialthat the shape and surface smoothness of the various working portions ofthe point he precision formed to close tolerances. I

With the foregoing in inind, it is therefore a major objectofmy-invention to provide a method for forming ball pen points ofsuperior and uniform quality.

ir d States .2 1

An equally important object of the invention is to provide a method forforming ball pen points at a high production rate without hand finishingoperations.

It is another object of my invention to provide a method for coining orswedging the ball against 'the bottom of the socket and folding the rimagainst the ball in a two step operation, to form an improved ball seatand a correct rim angle for avoiding rim dents in further operations.

These and other objects and advantages of the invention will becomeapparent from the following detailed description of the method and apreferred embodiment of the apparatus, and from an inspection of theaccompanying drawings in which:

Fig. 1 is a longitudinal section through a swedging apparatus forforming the ball seat and the point rim;

Fig. 2 is a diagrammatic plan view of the operating stations on aworktable;

Fig. 3 is an enlarged partial section through the first swedge and thetip of the pen point;

Fig. 4 is a greatly enlarged section taken in the area of the circle 4of Fig. 3;

Fig. 5 is a view similar to Fig. 3 showing the second rim angle swedgein position;

Fig. 6 is a longitudinal section through a spinning apparatus forexpanding the rim material;

Fig. 7 is a cross section taken along the line 7-7 of Fig. 6;

Fig. 8 is an inverted perspective view of the spinning roller head;

Fig. 9 is a bottom plan view of the spinning roller head;

Fig. 10 is a schematic view showing the relationship of a pair ofspinning rollers to the pen point;

Fig. 11 is a diagrammatic view taken in the direction of the arrow 10 ofFig. 6; and

Fig. 12 is an enlarged section through the tip of the pen point.

Referring now to the drawings and particularly to Figs. 1 and 3 thereof,the numeral 15 designates generally a ball pen tip or point assemblycomprising a tubular body or shell 16 rotatably supporting a forwardwriting ball 17. Body 16 has an internal bore 18 therein leadingforwardly to a socket 19 in which ball 17 is mounted, and serves tosupply ink to the back face of the ball. After completion, point 15 isattached to an elongated ink reservoir or cartridge opening into bore 18and is ready for use in a pen.

Point body 16 is initially machined to shape by conventional methodswith the side walls of socket 19 opened so that ball 17 may be fittedfreely therein. As is indicated in the. diagrammatic view of Fig. 2, themachined point body 16 may be mounted on a rotatable work table 20 forfinishing operations. Table 20 has a plurality of work stations 21spaced circiunferentially and adapted to hold a point body 16 inupstanding position. As table Ztl is indexed, stations 21 are brought inalignment under different working heads for performing sequentialfinishing operations.

In general, the manufacturing of a point requires three steps. First,the ball 17 is dropped or inserted into socket 19. This is done byconventional mechanisms and forms no part of my invention. Secondly, diemeans are employed to seat ball 17 against the bottom of socket 19 andfold the side walls of the socket inwardly over the equator of the ball.The folded side wall portions of socket 19 form a rim surface 24 whichis of forwardly tapering frusto conical shape and is terminated by athin annular lip or edge 25. Ball 17 is engaged downwardly against aspherical beveled surface 26 surrounding the top of bore 18. Followingthese swedging steps, the rim is subjected to a rolling operation withroller means bearing against the outer or rim angle surface 24 to ironout the material lying between the rim angle and ball 17, causing thematerial to expand. This expansion creates a clearance between ball 17and the inner wall of rim 24 to define a metering section 28 in theregion above the equator of the ball to control the rate of ink flow.

, In Fig. 1, I have illustrated a simplified form of swedging apparatuswhich is capable of carrying out the swedging or coining operations aswill now be considered in more detail. Typically, fixed frame member 30supports a vertically reciprooab'le spindle 32 which is moved up anddown by means of an upper collar 33 that is connected to a reciprocatingmechanism (not shown). Spindle 32 is held against rotation within frame30 by vertical keys 33 which slide in grooves formed in the frame.

Mounted at the bottom end of spindle 37 is a female swedging die 36having a central upwardly open working surface 37 of generally conicalshape. The axis of surface 37 lies along the axis of spindle 31, and die36 is held fixedly to the spindle by a lower locking cap 38 which isflanged outwardly and threadedly engaged to the spindle.

Spindle 32 is positioned in vertical alignment with one of the workstations 21 on table 20 so as to extend coaxially with the longitudinalaxis of the upstanding pen point 15. As spindle 32 is moved downwardlyagainst point 15, working surface 37 bears downwardly against the pointwith a gradually increasing pressure. Die 36 is the first of two diesused in the swedging operation, and its exact shape and relationship topoint 15 must be considered in detail.

Referring to Fig. 3, it will be seen that a lower section 40 of workingsurface 37 is offset slightly from the upper section and is adapted tobear against the angular surface of rim 24. An adjacent upper section 41of surface 37 is spaced inwardly by a step or shoulder 42 and is offrusto spherical shape so as to seat solidly against the surface of ball17. Shoulder 4-2 is formed with a small radius corner so as to have adownwardly and inwardly directed sectional profile. It should also benoted that die surface 40 and the rim angle 24 formed thereby, lie at arelatively more obtuse angle with the axis of point 15 than in thefinished point shown in Fig. 4.

First swedging die 36 has two functions; that of pressing ball 17downwardly to form seat 26, and that of partially folding the rim angle24 and lip 25 inwardly. As die 36 descends the initial pressure isapplied to ball 17 so as to form seat 26. At this time, substantiallyall of the pressure is applied to ball 17 and seat 26 .is swedged orcoined into a very smooth surface with all initial burrs or flaws beingremoved.

A light and gradually increasing pressure is applied to rim angle 24 sothat it folds inwardly to conform to the die surface 40 as die 36continues to descend. During this time, the arcuate shoulder 42 bearsdownwardly against rim lip 25 so as to form a rounded semi-circular orcrowned surface which provides a small annular corner or pocket bet-weenthe rim lip and the adjacent surface of ball 17. The purpose of thisinner angle or radius is to smooth out such irregularities in the lip asmay remain after machining operations. Although such burrs may bemicroscopic in nature, they tend to interfere with a smooth flow of inkfrom the point, and form jagged or rough edges which pick up lint as thewriting ball travels over the surface of the writing paper.

Another feature of the radiused type step die 36 is that it performs lip25 into such a shape as to have less tendency to wrinkle or break whenthe subsequent rolling or spinning operation is carried out. Theelimination of sharp corners upon rim lip 25 permits a greater degree ofdistortion without wrinkling or rupture. 'Dhe principle of this may beexplained by considering the greater difficulty involved in bending asquare sectioned bar I the surface of ball 17.

4 without edge wrinkling, than in bending a bar of round section. a

In prior finishing operations, it has been considered sufiicient to seatball 17 in' the manner described, and to form an obtuse rim angle 24 byswedging with a single die which was of sutficiently fiat angle toperform both functions. The point 15 was then moved directly into aspinning or rolling operation where the rim angle 24 was made more acuteby the action of spinning rollers. This prior method has not beensatisfactory, and two major defects are found in points so produced.Because the pressure is divided between ball 17 and rim angle 24, theinternal wall surface of the rim in the metering section has not beenworked sufficiently to smooth out any machining flaws which mightremain. Also, when rollers are used to change the shape of rlrn angle 24a sharp hump or corner is initially presented to the rollers and theimpact of the rollers against the rim often produces rim dents whichcannot be smoothed out.

To overcome these difficulties, I have introduced a second swedgingoperation which takes place before the rolling or spinning operation.For this step, I use a second female swedging die 44 which is seen inFig. 5. Die 44 is adapted to be supported in the type of apparatus asshown in Fig. 1 for reciprocating movement. The bottom of die 44 isformed with an upwardly open conical working surface 45 which is ofsimple, straight walled shape, and is at an acute angle with the axis ofpoint 15 corresponding exactly with the inclination of the rim angle 24desired for the finished point. Because of its acute angle, surface 45passes above and does not engage with Thus, as downward pressure isapplied, surface 45 transmits its entire impact value to rim angle 24and is able to smooth out the interior wall surface of the rimwithoutany damping action as would occur if part of the pressure weretransmitted to the ball.

In changing the shape of rim angle 24, die surface 45 actssimultaneously against the-entire circumferential area of the rim angle.This action does not apply pressure at a single area of contact as inthe case of a roller, sci that there is no possibility of a localizeddeformation or dent. When rim angle'24 is completely formed by theaction of surface '45, it has the exact angle of inclination of thefinished point. Therefore, the subsequent action of spinning rollers hasmuch less tendency to cause rim dents.

The remaining operations, performed upon point 15 is illustrated inFigs. 6 to 11, and is primarily concerned with producing the correctclearance between ball 17 and the wall of rim angle 24 in the meteringsection 28. Some prior methods of spinning or rolling the point haveapplied pressure to both the rim wall and the ball in an attempt tocontrol the clearance developed by the rolling action. However, thesemethods divide the pressure between the ball and rim so that in order towork the rim properly it is necessary to apply considerable pressure tothe surface of the writing ball. In applying such pressure to the ballthere is a strong possibility that the highly finished surface of theball will be marred so that erratic writing qualities may develop. Thisis particularly true in the case of writing balls made of relativelysoft stainless steel such as are used with acid-type quick drying inksto avoid corrosion.

The principle of rim expansion used to develop the clearance in themetering section of the point is that pressure applied against the rimangle causes a gradual decrease in the thickness of the rim wall. Sincethe same volume of material is present in the rim before and afterrolling, the result is that the rim must expand circumferentially andthereby develop clearance with the adjacent portion of the ball surfacein the metering section of the point. This determines the flow rate ofink from the point and hence the line shading of the writing.

While the application of pressure to both the rim and the ball has thedisadvantages above stated, there have also been found to be seriousdifficulties with the applicaaorta-ere tion of pressure solely to therim wall of the point using prior rolling methods and apparatus. Theprinciple objection found in prior rolling means used against the rimalone has been that the rim lip becomes distorted and broken down intoan irregular shape before sufficient rim expansion has taken place. Suchan irregular rim lip surface tends to accumulateink, and to gouge intothe Writing paper and collect lint which soaks up even more ink andsmears the Writing paper from time to time.

To overcome these objections, I provide rolling means which tend to rideup the surface of the rim angle as well as circumferentially around it.This prevents the flow of material along the rim angle toward the rimlip so that the latter is left in the smooth and regular shape formedduring the swedging operation. Enough pressure can be applied to causethe desired amount of rim expansion without any breakdown of the rimlip.

Referring now to Fig. 6, a simplified form of apparatus for performingthe rolling operationis shown. It is to be understood that the structurefor reciprocating and rotating the spinning or rolling head may berefined considerably without changing the principles of my invention.Typically, a frame member 50 rotatably supports a sleeve 51 by means ofball bearings 52. Mounted for vertical reciprocating movement withinsleeve 51 is a driving spindle 53 which is moved up and down by a collar54 adapted to be connected to a reciprocating mechanism (not shown).Spindle 53 is keyed for rotation with sleeve 51 and the latter is formedwith a pulley 55 thereon adapted to be engaged with a belt 56 forrotational drive.

At the bottom of spindle 53 is a mounting head 58 on which arepositioned a plurality of circularly spaced rollers 59. Pen point 15 isheld in work table 20 and is brought beneath head 58 so that thelongitudinal axis of the point is aligned with the axis of spindle 53.Rollers 59 are so mounted as to engage the rim angle 24 of the point andbear thereagainst as they rotate about their own axes and revolve aroundthe axis of the point.

Due to tolerances in machine construction, it is diflicult to obtainexact alignment of the axes of point 15 and spindle 53. To prevent anyeccentricity in the rolling of rim angle 24, I provide a floatingconnection between spindle 53 and head 58 which permits the head toalign exactly with the axis of point 15. Threadedly connected to thelower end of spindle 53 is a holding socket or nut 61 which isinternally opened to form a circular chamber 62. Mounted loosely withinchamber 62 and spaced downwardly from the bottom of spindle 53 is thehead 58 which is of cylindrical shape having an outwardly flared upperportion 63. A complementa-l inwardly beveled flange64 on nut 61 preventshead 58 from falling out of chamber 62, and tends to center the headwhen the latter drops downwardly.

Between head 58 and spindle 53 is a flat circular retainer plate 65 inwhich are mounted a plurality of balls 66 which serve to transmit thrustloads between the spindle and the head. To rotate head 58 with spindle53 spaced driving cleats 67 are extended downwardly from the spindle andengaged loosely in slots 68 formed in plate 65. Similar driven cleats 69extend upwardly from head 58 and engage in slots 70 as is best seen inFig. 7. By this arrangement, head 58 may shift slightly from side toside and incline from the vertical while remaining rotatably connectedto spindle 53.

The particular arrangement of rollers 59 upon head 58 is very importantand may best be understood by considering Figs. 8 and 9. The bottomsurface of head 58 is defined by a plurality of inwardly and downwardlyin of the surfaces 72. Blocks 73 are of elongated rectaii gular shapeand rotatably support rollers 59 by means of central pin 74 whichextends exactly perpendicular to the upper or seating surface of theblock. Preferably, rollers 59 are mounted on anti-friction bearings andhave a hardened and highly polished outer surface. To attach blocks 73to head 58, individual fastening bolts 75 are threaded-upwardly into thehead near the outer ends of the blocks. This, of course, also permitsconvenient replacement of the rollers.

While the holding blocks 73 lie flat against the surface 72, they arenot directed exactly toward the axis of head 58 as can be seen from aninspection of Fig. 9. Rather, each block 73 is ofiset slightly oradvanced in the direction of rotation from the center of its supportingplane 72, and directed slightly to the side of the head axis with all ofthe blocks being oifset in the same direction and in the same amount toprovide a symmetrical arrangement. In other words, a plane which ispassed through the axis of each roller 59 and the longitudinalcenterline of block 73 is parallel to, but offset or spaced from theplane which is passed radially through the axis of nose 58 and thecenter of the surface 72. The effect of this is to shift the axis ofeach roller 59 out of any plane passed through the axis of head 58, andto incline each roller at, what I define as a compound angle with theaxis of point 15. Accordingly, the line or element of contact betweenthe surface of rollers 59 and the rim angle surface 24 is inclined intwo directions from the axis of the point. This is the same as sayingthat since the axis of the head 58 and the axis of the roller 59 do notlie in a single plane they cannot be relatively positioned by referenceto a single planar angle between them.

As will be remembered, the axis of pen point 15 is held coaxially withthat of head 58. Accordingly, the rim angle surface 24 is a surface ofrevolution traced about the axis of head 58. Also, it can be seen thatrotation of head 58 causes rollers 59 to revolve around the head axis ina path which is a surface of revolution thereabout. Because the rollers59 are geometrically formed concentric with their own axes it can beappreciated that the contact between the surfaces of the roller is not apure rolling engagement, but includes a component of sliding engagement.

The effective relationship of rollers 59 to rim angle surface 24 is bestseen in the diagrammatic views Figs. 10 and 11. The line ofcontactbetween the surface of rollers 59 and rim angle surface 24 istilted out of the vertical plane back away from the axis of rotation ofthe rollers. The amount of inclining is indicated by the angle A inFigure 11. The offset between the plane passed radially through the axisof point 15 and the plane passed through the axis of roller 59 isrepresented by the distance X this being the offset distance as wasdescribed in the next to preceding paragraph.

As viewed in Figure 11, the rollers 59 would be revolved around thepoint 15, in a clockwise direction as seen from above, by rotation ofhead 58 about its own axis. Since rollers 59 are free to rotate abouttheir own individual axes they would at the same time rotate in acounterclockwise direction as seen from above.

In the operation of the device, the angular relationship just described,and the direction of rotation is such as to cause rollers 59 to tend toride up the surface of rim angle 24 toward rim lip 25. That is, asrollers 59 rotate about their own axes and revolve about the axis ofpoint 15, they slip or slide frictionally down the surface of rim angle24 as well as rolling along the circumference thereof. The pressureexerted by rollers 59 on rim angle 24 tends to thin the material of therim wall and cause it to expand outwardly from ball 17. This producesthe desired amount of clearance in metering section 28. At the sametime, the component of downward sliding motion of rollers 59 preventsany upward flow of material toward rim lip 25. Thus the finished pointhas the desired clear- 7 ance without any distortion of the smooth andregular surface of rim lip 25. V I

While I have thus shown and described in some detail my method offinishing a ball pen point and a preferred form of apparatus toaccomplish the method, it is to be understood that changes of design andconstruction can be made without departing from the scope of theinvention. Therefore, I do not Wish to be limited by the foregoingexcept as defined in the appended claims.

I claim:

1. In a method of producing a desired clearance between a ball and theinner walls of a cavity in the nose of a member in which said ball isheld the improvement which eliminates marring of the surface of the balland maintains a smooth lip on the rim of said nose consisting of thesteps of: applying pressure at spaced points about the rim of said noseby direct contact through pressure applying surfaces with said rimalone; rotating said pressure applying surfaces about an axis which isnon-planar with the longitudinal axis of said nose; and simultaneouslyrevolving all of said pressure applying surfaces about said axis in adirection to expand said rim away from said ball and resist the flow ofrim material towards said lip.

2. In a method of forming a ball pen point wherein a ball is pressedinto a cavity formed in the nose of the point, the rim of the point isfolded over to retain the ball, and a desired clearance is producedbetween the ball and the inner wall of the nose the improvement whichconsists in the steps of: applying a pressure in direct contact with theball to seat said ball in the nose cavity; simultaneously applying apressure in direct contact with the nose rim to partially fold said rimradially inwardly against the ball; subsequently applying a pressure indirect contact with the nose rim alone to finish folding said riminwardly against the ball to the desired rim angle; applying pressure atspaced points about the rim of said nose by direct contact throughpressure applying surfaces with said rim alone; rotating said pressureapplying surfaces about an axis which 'is non-planar with thelongitudinal axis of said nose; and simultaneously revolving all of saidpressure applying surfaces about said axis in a direction to expand saidrim away from said ball and resist the flow of rim material towards saidlip.

3. In a method of producing a desired clearance between a ball and theinner walls of a cavity in the nose of a member in which said ball isheld the improvement which eliminates marring of the surface of the balland maintains a smooth lip on the rim of said nose consisting of thesteps of; applying pressure at spaced points about the rim of said noseby direct contact through pressure applying surfaces with said rimalone, rotating each of said pressure applying surfaces about anindividual axis which is non-planar with the longitudinal axis of saidnose; and simultaneously revolving all of said pressure applyingsurfaces about said axis in a direction to expand said rim away fromsaid ball and resist the flow of rim material towards said lip.

References Cited in the file of this patent UNITED STATES PATENTS1,798,738 Hoern Mar. 31, 1931 2,167,654 Hothersall Aug. 1, 19392,216,878 Densmore Oct. 8, 1940 2,234,182 Lauer Mar. 11, 1941 2,257,566Lewis Sept. 30, 1941 2,414,598 Klipper Jan. 21, 1947 2,498,009 SchraderFeb. 21, 1950 2,646,761 Knobel July 28, 1953

